Method of Treatment and Perforation of Near-Well Zone

ABSTRACT

A method of treatment and perforation of a near-well zone of oil and gas recovery wells, includes making an oil or gas recovery well in deposits with carbonate collectors, performing slotting opening by sand treatment with a jet containing sand and a sand carrying liquid, and using as the sand carrying liquid a sand carrying liquid which contains light hydrocarbons C 3 -C 12 .

BACKGROUND OF THE INVENTION

The present invention generally related to oil and gas industry and inparticular to methods of treatment and perforation of oil- andgas-producing wells.

In the processes of oil and gas recovery the efficiency of the processsignificantly depends on a permeability of oil and gas containingformations on on a radius of carrying out of the process. The higher thepermeability of the oil or gas deposit and the greater the radius ofcarrying out of the process, the greater the quantity of oil and gasrecovered and the higher is the efficiency of the recovery process. Forthis reason efforts have been made to increase the permeability of thegas and oil containing formations and to increase the radius of carryingout of the process of oil and gas recovery. It is believed that theexisting processes of treating and perforation of the near-well zone ofgas and oil wells can be further improved.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide amethod of treatment and perforation of near-well zone which is a furtherimprovement of existing methods of this type.

More particularly it is an object of the present invention to provide amethod of treatment and perforation of near-well zone which allows toimprove permeability of formations and to increase radius of covering ofthe formation for gas an oil recovery.

In keeping with these objects and with others which will become apparenthereinafter one feature of the present invention resides in that in aprepared well located in a deposit with carbonate collectors, a slottingopening is performed by sand treatment with a jet containing sand and acarrying liquid, and the sand carrying fluid which is used, containslight hydrocarbons C₃-C₁₂.

In accordance with another feature of the present invention, theslotting opening is performed with a pressure of the sand-carryingliquid selected so that the hear-well zone of the well is saturated withthe above mentioned light hydrocarbons.

A further feature of the present invention resides in that in order toobtain the desired pressure of the sand-carrying liquid a valve isprovided in a return line for conveying the sand and liquid containingjet.

It is another feature of the present invention to use as a lighthydrocarbons individual paraffins of a row C₃-C₁₂ or their mixtures,such as benzene, kerosene, diesel fuel etc.

Still another feature of the present invention resides in that at andend of the slotting opening the pressure of supplying the sand andliquid containing jet is reduced to reduce a speed of circulation of thesand and liquid jet and to provide partial deposition of sand andfilling of cracks, of perforation channels and partially of a well boreto enhance uniform saturation of a formation with the light hydrocarbonsto initiate a process of liquid oxidation of the light hydrocarbonsinside the formation.

In accordance with a further feature of the present invention thenear-well zone is heated to, and then after the heating an air is pumpedinto the well to produce a highly efficient acting agent comprising amixture of carbonic acids and solvents.

The novel features of the present invention are set forth in particularin the appended claims.

The invention itself however will be best understood from the followingdescription of preferred embodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the present invention it is proposed to treat andperforate a near-well zone of oil or gas recovery wells so as to improvepermeability and radius of action. The inventive method is used oil andgas recovery wells which are made in zones with carbonate collectors. Aslotting opening is performed with the use of a sand containing jetwhich has sand and a sand carrying liquid. The sand carrying liquid inthe inventive method includes light hydrocarbons C₃-C₁₂. As the abovementioned hydrocarbons, individual parafins of homological raw C₃-C₁₂ ortheir mixtures can be utilized, including benzene, kerosene, dieselfuel, etc.

The slotting opening is performed with a pressure in the well, which isnecessary for saturation of the near-well zone with the above mentionedlight hydrocarbons C₃-C₁₂. This pressure can be obtained by using avalve provided in a return line of the flow of the sand and the sandcarrying liquid containing jet. At the end of the slotting opening thepressure of pumping of the above mentioned medium is reduced. Therebythe speed of its circulation is reduced as well, and a partialdeposition of sand takes place, and the sand fils cracks, perforationchannels and partially a well bore.

The presence of sand in these cavities results in obtaining a moreuniform saturation of the formation with the light hydrocarbons C₃-C₁₂,so that the process of their oxidation inside the formation can beguaranteed, and a possibility of explosion in the well is prevented.

Then, a warming up of the near-well zone of the well is performed totemperature of 150-200 degrees C. This operation can be performed withthe use of chemical reactants which generate heat during theirinteraction with each other. On the other hand, the warming up can beperformed by an electric heater designed to operate at certain depths.

After warming up of the near-well zone, air is pumped into the well borein the quantity of 2,500-12,500 cubic meters per 1 meter of perforationinterval. This quantity of air is needed to produce directly in theformation 1.5-7.5 t per 1 meter of perforation interval a highlyefficient acting agent, containing a mixture of carbonic acids (formicacid, acetic acid, etc.) and solvents (ketons, alcohols, ethers etc.).After a certain time is maintained, the well is discharged and is readyfor operation.

It has been established in a new, unobvious way that the carrying out ofreaction of oxidation inside the formation with temperatures below 150degrees C. can lead to an interruption and stopping of the process. Onlyan insignificant amount of the acting agent will be produced in theformation. On the other hand, the upper limit of the temperature of 200degrees C. is determined by the situation that the higher temperature ofreaction of the liquid phase oxidation inside the formation can lead toa fire-generating reaction.

Example of the tests of the inventive method are presented hereinbelow.

EXAMPLE 1

A well is provided in a carbonate collector in interval 1,220-1,228 m,effective thickness 4 m, porosity of collector 12%, formation pressure12 MPa, reception of the well 1 cubic m per day with repression of 10MPa. A slotting opening is performed with a speed of movement of thesand perforator 5 mm/min, liquid supply through the perforator 9 l/sec.

Time of opening 14 hours. The liquid used as sand carrier is benzene.

After the opening the reception of the well 15 cubic m per day forliquid with 10 MPa repression. A valve is arranged in a return line,which provided an inlet pressure of 13.1 MPa with the flow rate ofliquid through it 9 l/sec. The repression during this 10 MPa, and 9cubic m of benzene is introduced in the process of slotting opening.Then the pressure of the liquid solution which is being pumped isreduced to 4 MPa, the speed of circulation of the solution diminishes,and the process of filling of cracks, perforation channels and partiallyof well bore with sand starts.

During the process of filling the cavities with sand, 150 kg ofgranulated magnesium is added, and the perforator is lifted above theproductive formation to avoid it blocking. The height of the thusly madeartificial filter is determined by quantity of sand dispersed in theliquid in the working solution and granulated magnesium. In this casefor forming the filter the quantity of sand was 450 kg, and of magnesium150 kg.

Then 2.8 cubic m of hydrochloric acid with 20% concentration is pumpedinto pump-compressor pipes. It interacts with the granulated magnesiumand provides warming up of the near-well zone to 150-160 degrees C. Thenair is pumped in with the quantity of 22,500 cubic m.

The well is placed on hold for 48-50 hours, then discharged, and putinto operation.

EXAMPLE 2

Well opened a carbonate collector of oil in interval of 1,220-1,228 m.Effective thickness is 4 m, porosity is 12%, formation pressure 12 MPa,reception of the well 2 cubic m per day for liquid at repression of 10MPa. slotting opening of the formation is performed with speed ofmovement of the sand blasting perforator 5 mm/min, with flow rate ofliquid through the perforator 9 l/sec. the time of opening is 14 hours.As the liquid for carrying sand, a mixture of light hydrocarbons C₃-C₁₂is utilized. After the opening the reception of well is 15 cubic m perday for liquid at repression of 10 MPa.

A valve is arranged on the return line to provide an inlet pressure of13.1 MPa, at flow rate of liquid through it of 9 l/sec. With this therepression is 100 MPa, and during the slotting opening 9 cubic m ofmixture of light hydrocarbons is into the formation. Then the pressureat the inlet of the well (of the working agent) is reduced, and theprocess of filling crack, perforation channels and partially of wellbore will start. During the process of filling of the cavities with sandthe perforated is lifted above the productive layer by 5-6 m to preventits locking. The height of the artificially created filter is determinedby the quantity of sand suspended in liquid. In this case for formingthe filter the quantity of sand was 450 kg.

Then the sand-blasting perforator is removed from the well, and a gasburner is lowered to be located directly above the artificial filter,and the near-well zone is warmed up to 200 degrees C. The gas burner isthen turned off, and 22,500 of cubic m of air is pumped into the well.The well is placed on hold for 48-50 hours, then discharged, and thenput into operation.

The utilized light hydrocarbons can include any hydrocarbons ofhomological raw C₃-C₁₂ individually or in mixtures. As an example suchhydrocarbons as butane, lentane heptane etc can be used. Also theirmixtures can be used, such as unstable benzene from gas-processingplant, head of oil stabilization in oil excavations, light gascondensates.

The present invention significantly increases the efficiency oftreatment of near-well zone as a result of deeper and more uniformpenetration into a formation of products of reaction of liquid-phaseoxidation in the formation of light hydrocarbons C₃-C₁₂, which improveshydrodynamic properties of the collector.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofmethods differing from the types described above.

While the invention has been illustrated and described as embodied in amethod of treatment and perforation of near-well zone, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:
 1. A method of treatment andperforation of a near-well zone of oil and gas recovery wells,comprising the steps of making an oil or gas recovery well in depositswith carbonate collectors; performing slotting opening by sand treatmentwith a jet containing sand and a sand carrying liquid; and using as thesand carrying fluid a sand carrying fluid which contains lighthydrocarbons C₃-C₁₂.
 2. A method of treatment and perforation of anear-well zone of oil and gas recovery wells as defined in claim 1,further comprising performing the slotting opening with a pressure ofthe sand-carrying liquid selected so that the hear-well zone of the wellis saturated with the light hydrocarbons.
 3. A method of treatment andperforation of a near-well zone of oil and gas recovery wells as definedin claim 2, further comprising obtaining the pressure of thesand-carrying liquid by providing a valve in a return line for conveyingthe sand and liquid containing jet.
 4. A method of treatment andperforation of a near-well zone of oil and gas recovery wells as definedin claim 1, further comprising using as the light hydrocarbonsindividual paraffins of a row C₃-C₁₂ or their mixtures, includingbenzene, kerosene, diesel fuel.
 5. A method of treatment and perforationof a near-well zone of oil and gas recovery wells as defined in claim 2,further comprising, at and end of the slotting opening reducing thepressure of supplying the sand and liquid containing jet to reduce aspeed of circulation of the sand and liquid containing jet and toprovide partial deposition of sand and filling of cracks, of perforationchannels and partially of a well bore to enhance uniform saturation of aformation with the light hydrocarbons to initiate a process of liquidoxidation of the light hydrocarbons inside the formation.
 6. A method oftreatment and perforation of a near-well zone of oil and gas recoverywells as defined in claim 1, further comprising heating the near-wellzone, and after the heating pumping air into the well to produce anefficient acting agent comprising a mixture of carbonic acids andsolvents.
 7. A method of treatment and perforation of a near-well zoneof oil and gas recovery wells as defined in claim 6, further comprisingperforming the heating to a temperature of 150-200 degrees C., andperforming the pumping of air in a quantity of 2,500-12,500 cub meterson 1 meter of interval of perforation.
 8. A method of treatment andperforation of a near-well zone of oil and gas recovery wells as definedin claim 6, wherein the heating includes heating in a manner selectedfrom the group consisting of heating by reactants which generate heatduring their reaction and by a depth electric heater.